Hydraulic lift apparatus



March 15, 1960 E. R. PRECIADO HYDRAULIC LIFT APPARATUS Filed Feb. 4, 1957 Unite This invention generally relates to a hydraulic lift mechanism, and is more particularly directed towards a hydraulic jack operatively connected to and actuated by a hand pump.

An object of the present invention is to provide a simple low-cost hydraulic lift unit which is adapted for releasable connection to an object whose elevational position is required to be selectively varied, such as the pivotally mounted distributing trough or chute of a concrete mixer truck.

Another object of this invention is to provide apparatus of the character described in which a low pressure, high volume manually operable pump is connected with the jack so as to materially speed up the operation thereof.

A further object of this invention is to provide apparatus of the type referred to which is extremely simple in construction and operation and which may be readily fabricated from conventional pipe fittings and other readily accessible standard materials.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawing accompanying and forming part of the specification. It is to be understod, however, that variations in the showing made by the said drawing and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawing:

Figure 1 is a perspective view of the hydraulic lift apparatus of the present invention.

Figure 2 is a vertical cross-sectional view of the lift mechanism.

In broad terms, the apparatus of the instant invention includes a longitudinally extending jack assembly generally designated by the numeral 6, and a manually operable hydraulic pump, indicated by the numeral 7. Such pump may be of conventional construction and wiil be seen to include a plunger mechanism 8 which is actuated by a manually engageable handle 9, and a lever 12 is provided for effecting a release of the pump pressure. This pump 7 is adapted to effectuate a high volume low pressure flow upon handle actuation, such pressure being less than 1500 pounds per square inch. In this manner, a relatively few strokes of the handle 9 by the user will effect a substantial flow of hydraulic fluid and consequently a fast and responsive action on the part of the jack. The pump may be provided with a discharge fitting 13, and such fitting is operatively connected to a flexible hose 14 whose other end is connected to the jack 6.

Referring now to the jack 6, the same will be seen to include a cylindrical body 16 having an internal diameter in the neighborhood of 1 /2 inches and providing a chamber 17. Access is had to the chamber 17 from exteriorly of the body through a fitting 19 which releasably receives the other end of the pump hose 14. In this manner, hy-

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draulic fluid may be operatively'pumped into the cham-' ber 17 for a purpose presently to be explained. Disposed substantially immediately subjacent the fitting 19 is a plug 21 the body, such plug being welded or otherwise suitably secured to the body. The portion of the body below the plug is provided with a pair of diametrically opposed notches 22 so as to sions 23 which are apertured as indicated at 24 whereby the entire jack may be suitably pivotally mounted adjacent its base on a supporting pin or shaft (not shown).

Positioned within the chamber 17 of the body is an axially extending plunger 26 whose outside diameter is pipe bushing reducer 29 which is externally threaded and engaged with the threads on such body end. The reducer is provided with a flange 31, the inner peripheral surface of which is grooved to receive an O ring 32 which forms a seal with the peripheral surface of the plunger 26. The lower end of plunger 26 is provided with an axially extending threaded stud 36 and such stud is adapted to receive an inverted cup shaped packing 37 which may be maintained against the lower surface of the plunger as well as against the inner peripheral surface of the body 16 by nuts 38 and a pair of washers 39. Also, to provide a guide for the lower end of the plunger a brass bushing 41 is utilized which is placed in the annular space 27 adjacent the packing 37.

As .will be seen in the drawing, the upper end of the plunger is provided with a generally flat rectangular extension 46 disposed in diametrical relation to the upper surface 47 of the plunger. This extension is provided with a generally centrally positioned aperture 48 by means of which the plunger may be pivotally attached to the unloading chute of a concrete mixer truck or any other device which is to be selectively raised and lowered by the jack.

From the foregoing description the details of construction as well as the mode of operation of the unit should be apparent. In order to use the jack, it is only necessary to connect the hose 14 between the fittings 13 and 19 on the pump and jack respectively. Then, with the pump control lever 12 in its proper position the operator may pump hydraulic fluid through the hose and into the chamber 17 between the stationary plug 21 and the plunger packing 37. This will, of course, result in the plunger rising in the body 16, and due to the packing and the O ring seal 32, there will be no danger of fluid leakage. Contra positioning of the lever 12 will permit a downward descension of the plunger.

I By having a minimum friction area between the plunger .and the body 16, low pressure fluid may be utilized in raising and lowering the plunger with a minimum of binding. Actually, the bushing 41 is utilized primarily as a guide to center the lower portion of the piston and the only frictional seal is effected at the packing and Oring respectively. Obviously, the inner diameters of the reducer 29 and bushing 41 are the same and effectively guide the plunger along the longitudinal axis of the jack body even where an eccentric load may be positioned on the plunger extension.

While the apparatus is extremely simple in construction and operation it fulfils a definite need in providing a. low cost unit for the previously discussed purposes, or for use in other installations where rapid vertical or other adjustments are required, since the jack constructionpermits proper operation irrespective of the angular disposition thereof relative to a vertical plane.

which completely seals a lower end portion of define diametrically opposed extena a V. 7% What is claimed is: 1. Apparatus of the character described comprising a within said chamber adjacent said sealingmeans, a cylin- Y drical plunger disposed in said chamber and defining with cylindrical body member, plug means sealing a'lower end portion ofsaid body member, a plunger of cylindrical configuration positioned within said body and spaced from the wallth ereof, means carried by the lower end of said plunger a'ridextending laterally therefrom tojsealably and slidably engage'ithe'wall ofsaid body, guidemeans intermediate said plunger and said body adjacent said seal means,land guide meansonand adjacent the upper end of said body including an O ring slidably, and seal: v,

ably engageable with the upper end portion of said plunger, the upper endof said plunger extending axially beyond said last named guide means and including an aperturedextension of generally fiat rectangular form extending diametrically across the upper surfaceof said plunger, and said body member having an integral apcrtu'red bifurcated lower endsubja'cent said plug "meairsand adaptedto receive pivotal supporting means. 2. Apparatus of the character described comprising al cylindrical body defining a chamber, means'sealing the lower'end portion or said body, means defining a hydraulic fluid passage from outside of 'said ch ambe'r to said body an annular space, said plunger having a downwardly directed threaded stud element, an inverted cupshaped packiiigpositioiied against said lower plunger surface, nut means engageable with said stud and releasably securing said packing in position, the upper end of said body member being internally threaded, an externally threadedbushlng engaged with said body member threads and including'a plunger guide portion having an 0 ring seal engageable with the per ipheral surface of said plunger, anda-metal guide bushing disposed in the annular space between'said plunger and body adjacent said Packing.

' R efer-en'c e 's'Cited inihe'file ofthis paten't UNITED STATES PATENTS Rockwell L. Apr. 15,-1952 

